MECA Team

The MECA team is an interdisciplinary team of Integrative Biomechanics combining biomechanics, ecophysiologists and molecular physiologists. It analyses trees' responses to wind and gravity around a generic question: ‘How do trees manage to stand upright for so long when they deploy their architecture in a fluctuating mechanical environment?’

In a context of climate change, where storms could become more frequent with weaker winds, the question of the mechanisms that enable acclimatisation and resilience to wind has become crucial.

Our findings show that the support function is active and linked to growth, enabling i) the mechanical structure of plants (height and diameter, rooting) to be adapted to prevailing winds during the growth period (thigmomorphogenesis) and ii) postural control (habit) via active tropic straightening processes that enable plants to recover from non-lethal mechanical accidents. It is the combination of these two processes that ensures the plasticity of the coupling between growth and support and enables a sustainable habit that is acclimatised to the mechanical environment.

A key aspect of these two processes is the phenomenon of mechanoperception of deformations and inclinations induced by gravity, wind or manipulation.

The physical and biological mechanisms involved are analysed from the cellular level to that of the tree's complete 3D architecture, with a strong focus on multiscale integration and constant back-and-forth between experimentation and modelling.

On the macroscopic scale of trees in natural conditions, we construct biomechanical perception-response models that enable us to identify, prioritise and formalise the physical and biological mechanisms involved in mechanosensation and morphogenetic responses. Particular effort is focused on identifying internally perceived mechanical variables and spatio-temporal variations in the plant's mechanical sensitivity based on its mechanical history. Work at the molecular scale focuses on early molecular events, and in particular on identifying the network of genes that determine mechanical sensitivity and its regulation. In this approach, we often use a combination of morphometric methods (continuous monitoring of growth rate with or without contact, 3D shape measurements), structural and fluid mechanics (test development, modelling) and molecular biology.

MECA Scientific Topics

• Long-distance signalling
• Soil/root impedance
• Proprioception and gravitropism
• Accommodation to mechanical stress
• Acclimatisation of trees to wind

MECA Tools

• Horizontal microscope
• Gravitron
• Mechanical characterisation tests
• Mechanical deformation control (bending)
• Electrophysiology measurements